An EHA, as a highly integrated local hydraulic actuator, is an execution mechanism in a power-by-wire actuating system of a more electric aircraft. Compared with a traditional hydraulic actuating system, the EHA has advantages such as small volume, light weight, and high efficiency, and is a hot research today. Furthermore, a load sensing way can decrease energy loss and reduce heat of an electrical motor.
At present, internationally, an EHA of fixed displacement variable speed sees wider application in a power-by-wire actuating system of an aircraft because it is light and has a simple structure. However, the system suffers a problem in radiation because of highly integrated design such that the EHA cannot work for a longer time under heavy load with low motor efficiency, large current and severe heating.
A solution to this problem at present is to take radiation of the system into consideration at the beginning of designing the system on the one hand, and to use a variable displacement pump to change a transmission ratio of the system by varying the displacement of the pump so as to improve power condition of the motor and reduce radiation on the other hand. While a variable displacement execution mechanism of the variable displacement pump mostly employs a servo valve to achieve variable displacement by controlling a hydraulic cylinder to drive a variable displacement mechanism of the pump, or an electrical motor actuator (EMA) to achieve variable displacement by driving the variable displacement mechanism of the pump. These two ways are complicated in structure and increases failure rate of the system.
A load sensing control system exhibits lower power loss and higher efficiency than a traditional hydraulic system. As high efficiency and low power loss means fuel saving and relatively low heating of the hydraulic system, a load sensing way is introduced into the EHA by some research centers. However, currently available load-sensing EHAs mostly use a servo valve to achieve direction change and control. The servo valve generates a large amount of heat during operation, which is not favorable for reducing heat of the system. As a result, in order to reduce heat of the system and mitigate energy loss, the present invention provides a novel load-sensing EHA energy saving device.